Immune System Flashcards Preview

IB Biology HL > Immune System > Flashcards

Flashcards in Immune System Deck (35)
Loading flashcards...

Define pathogen.

Any microorganism that can cause disease


What types of substances can be pathogens?

Bacterium, viruses, protazoa, fungi, and worms


How is a virus different from other pathogens?

Viruses require host cells to replicate and spread


Why can antibiotics be used to treat bacterial infections but not viruses?

Antibiotics target DNA transcription in bacteria, but not viruses, because of the structural and metabolic differences between bacterial cells and viruses.


What did Chain and Florey contribute to microbiology?

Chain and Florey tested the efficacy of penicillin in treating various diseases.


Outline the role of skin as a primary defense.

Act as a physical barrier of dead cells which cannot be affected by pathogens.


Role of hair in primary defense.

Sebaceous glands in hair follicles secrete sebum, which lowers pH and in turn inhibits the growth of bacteria and fungi.


Role of mucous as primary defense.

Mucous membranes secrete glycoproteins which trap pathogens and harmful particles.


Role of acidic conditions as primary defense

Lower pH inhibits bacterial and fungal growth


Role of lysozymnes as primary defense

Lysozymes in mucous act as an antiseptic, antibacterial enzymes


Function of erythrocytes

Carry oxygen to the body


Function of platelets

Prevent bleeding


Function of plasma

Carry proteins that help blood clot, transport substances, and other functions


Function of plasma proteins

Maintains electrolyte balance, blood viscosity, helps in clotting, causes inflammation, maintains acid-base balance


Outline blood clotting.

A blood vessel is damaged, triggering the release of chemicals and lead to platelets adhering to the damaged area. The chemicals then convert prothrombin into thrombin, an enzyme which in turn converts the soluble fibrinogen into the insoluble, mesh-like fibrin. The fibrin mesh fixes the wound.


Define leukocytes.

White blood cells. Help fight off pathogens.


What are phagocytes?

Phagocytes are leukocytes which eat other cells by phagocytosis.


What are macrophages? Describe their shape and size.

Macrophages are large, spherical phagocytes.


How do macrophages ingest pathogens?

They engulf pathogens by endocytosis and digest them with enzymes from lysozymes.


What is the difference between specific and non-specific immune responses?

Non-specific immune responses involve cells which are not specialized to a particular pathogen. Specific immune responses involve cells which are specially adapted to a particular pathogen.


Describe the structure of antibodies.

Antibodies are Y-shaped proteins composed of two heavy chains and two light chains bound together.


What produces antibodies? How many types of antibodies can each cell create?

Plasma cells produce antibodies and can only produce one type.


Explain how antibodies are produced.

A specific antigen type is identified and a specific plasma cell is identified that can produce an antibody which will bind to the antigen. The plasma cell clones rapidly and these new plasma cells begin antibody production. Antibodies then travel through the blood and destroy the pathogen.


Explain what happens to the plasma cells after antibody production.

Some antibody-producing plasma cells remain in the bloodstream and provide immunity against a second infection by the same pathogen, called memory cells. Memory plasma cells of this type make for faster immune response should the pathogen return.


Define antigen.

Any foreign molecule that can trigger an immune response.


What are common forms of antigens? Where are they found?

Antigens are proteins and very large polysaccharides. They are found on all cells.


What blood type is called a universal donor? What about universal receiver?

O blood type is known as a universal donor. AB blood is known as the universal receiver.


Explain how antibodies are produced.

Pathogen ingested by macrophage and its antigens are displayed on the macrophage's cell surface. Helper T-cells bind to the antigens and are activated. Activated T-cells bind to B-cells, activating them. Activated B-cells divide into plasma and memory cells. Making plasma cells is known as clonal selection. Antibodies are then produced in the extensive rER of the plasma cells.


Describe opsonization.

Make pathogen more recognizable to phagocytes.


Describe neutralization of bacteria and viruses.

Pathogens neutralize the pathogen and thus prevent them from entering cells.


Describe neutralization of toxins.

Antibodies bind to toxins and prevent them from affecting cells.


Describe activation of complement.

Antibodies activate a complement cascade which leads to the formation of a membrane attack complex that forms a pore in the membrane of the pathogen, allowing water and ions to enter the cell and thus causing it to lyse.


Describe agglutination.

Antibodies stick to pathogens so they can't enter cells and are easy to digest.


What is zoonosis?

Pathogen that can cross between species.


What is a histamine? What are their effect?

An amine released by mast cells when tissue is injured or in allergic and inflammatory reactions, causing dilation of small blood vessels and smooth muscle contraction. This allows for increased flow of immune components to the infected area.